As others have said, it is easy enough for a child in the 80s, with only a BASIC manual to come up with it. Been there, done that. Didn't even had a name for it. Later I read a magazine explaining several algorithms and found the name of what I had implemented.

For the curious, the ZX Spectrum microdrive listed files on the cartridges by order found on tape. I wanted to display it in alphabetical order like the "big" computers did.